Most electronic devices in use today include some form of intelligent control that is typically a single chip microcontroller. This microcontroller can be used to control general purpose integrated circuits that are used within the electronic device.
Cellular telephones, wireless modems, and wireless personal data assistants (PDAs) use a variety of radio frequency (RF) integrated circuits (RFICs) to provide connectivity to voice and data networks. Due to the nature of the wireless communications used in these devices, intelligent controllers are used to control the RFICs to optimize communications parameters such as signal-to-noise ratio and automatic volume control. These RFICs typically use GaAs ICs in which adding additional logic functionality to these RFICs increases the size, power and current consumption, and cost of the RFIC. Accordingly, to reduce the amount of logic required on GaAs chips a parallel bus is used to communicate between the microcontroller and the various RFICs. Thus, the number of lines that must be provided for each RFIC is equal to N*M where N is the number of bits in a data word and M is the number of RFICs.
However, as the size of integrated components used on a GaAs RFIC has decreased the power consumption of logic gates has decreased as well. In addition, as the interconnecting line size and circuit cell size decrease, parasitic effects between conductors in the RFIC increase. In particular, the large number of conductor interconnects used in the parallel bus between the microcontroller and the various RFICs creates parasitic inductances, capacitances, and cross talk interference. These parasitic effects reduce the data rate of the internal data communications between the controller and the various RFICs and may generate RF interference that can radiate and affect other components within the RFIC or the electronic device.
It would be desirable, therefore, to provide a communication link between a microcontroller and one or more control modules on an RFIC that does not require a parallel bus connection to transmit control and data messages to various RFICs.